My 3 month old sleeps in bed with me and has from the start. If I put him down away from me he's awake in 30 sec flat. Even in a cosleeper that is right next to me. He wants body contact.
He also sleeps best on his side. And yeah, flat on his back he starts coughing up stuff and choking and otherwise not breathing well at all. On his side? No problem.
I sleep with my arm curved around him. It's great.

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Mama to son Elijah and two rambunctious felines
Currently live in Minnesota